The following few things have saved me a lot with networks. It is the first things I do if I dont get internet or network connection.
Flush the DNS
Go to START → RUN and type in cmd
In the command promp window type in the following
C:\ipconfig -flushdns
Register the DNS
Your command prompt window should still be open from the previous exercise
In the command promp window type in the following
C:\ipconfig -registerdns
How to clear ARP Cache in windows Vista/XP/2003/2000
If the above mentioned steps still haven't fixed your problem, you should continue on to this step. The Address Resolution Protocol (ARP) is very crucial for TCP/IP network communication. If you begin to notice network connectivity problems such as particular web pages not loading or not being able to ping certain IP addresses then clearing your ARP cache is a good place to start.The TCP/IP ARP Command component provides the functionality to add, delete, or display the IP address for Media Access Control (MAC) address translation.
To flush/Delete the ARP cache in windows Vista/XP/2003/2000 follow this procedure
Click on Start—>Run—> type the following command click ok
netsh interface ip delete arpcache
Dynamic ARP cache entries update persist for 2-20 minutes depending on the system.
Windows 2003 Server = 10 minutes
Windows 2000 professional/Server = 10 minutes
Windows XP = 2 minutes
Solaris = 5 minutes
Delete IP address using arp command
arp -d <ip address>
Example
arp -d 10.1.1.2
Display arp table
arp -a
Add static entry to ARP table
arp -s <ip address> <mac address>
Example
arp -s 157.55.85.212 00-aa-00-62-c6-09
